Java JSON serialization - best practice

Question

I need to implement JSON serialization for some objects  and I ve encountered a problem when it came to integration with generic collections    All serializable classes implement this interface  JSONObject comes from this library    interface JSONSerializable      public JSONObject dump   throws JSONException   serializes object     public void load JSONObject obj  throws JSONException   deserializes object     Code for my collection based on java util list looks more or less like this   class AwesomeList lt T extends JSONSerializable gt  implements JSONSerializable      private LinkedList lt T gt  items   new LinkedList lt T gt                          public JSONObject dump   throws JSONException           JSONObject result   new JSONObject            JSONArray a   new JSONArray            for T i   items               a put i dump                       result put  items   a           return result             public void load JSONObject obj  throws JSONException            here is my problem           My problem is  When I load AwesomeList from JSONObject  I need to create its elements but it s impossible since java forbids me to write   T newItem   new T    newItem load obj     How should I modify my approach to this task

User · Answer

Have your tried json-io  https   github com jdereg json-io    This library allows you to serialize   deserialize any Java object graph  including object graphs with cycles in them  e g   A- B  B- A    It does not require your classes to implement any particular interface or inherit from any particular Java class   In addition to serialization of Java to JSON  and JSON to Java   you can use it to format  pretty print  JSON   String niceFormattedJson   JsonWriter formatJson jsonString

User · Answer

Are you tied to this library  Google Gson is very popular  I have myself not used it with Generics but their front page says Gson considers support for Generics very important

User · Answer

Well  when writing it out to file  you do know what class T is  so you can store that in dump  Then  when reading it back in  you can dynamically call it using reflection   public JSONObject dump   throws JSONException       JSONObject result   new JSONObject        JSONArray a   new JSONArray        for T i   items           a put i dump                inside this i dump    store  class-name            result put  items   a       return result     public void load JSONObject obj  throws JSONException       JSONArray arrayItems   obj getJSONArray  items        for  int i   0  i  lt  arrayItems length    i              JSONObject item   arrayItems getJSONObject i           String className   item getString  class-name            try               Class lt   gt  clazzy   Class forName className               T newItem    T  clazzy newInstance                newItem load obj               items add newItem             catch  InstantiationException e                   whatever           catch  IllegalAccessException e                   whatever           catch  ClassNotFoundException e                   whatever

User · Answer

As others have hinted  you should consider dumping org json s library  It s pretty much obsolete these days  and trying to work around its problems is waste of time   But to specific question  type variable T just does not have any information to help you  as it is little more than compile-time information  Instead you need to pass actual class  as  Class cls  argument   and you can then create an instance with  cls newInstance

[java] Java JSON serialization - best practice

Examples related to java

Examples related to json

Examples related to design-patterns